rhashtable: Add barrier to ensure we see new tables in walker

The walker is a lockless reader so it too needs an smp_rmb before
reading the future_tbl field in order to see any new tables that
may contain elements that we should have walked over.

Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Acked-by: Thomas Graf <tgraf@suug.ch>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 3 insertions, 0 deletions

diff --git a/lib/rhashtable.c b/lib/rhashtable.c
index 83cfedd6612a..618a3f00d712 100644
--- a/lib/rhashtable.c
+++ b/lib/rhashtable.c
@@ -477,6 +477,9 @@ next:
                 iter->skip = 0;
         }
 
+        /* Ensure we see any new tables. */
+        smp_rmb();
+
         iter->walker->tbl = rht_dereference_rcu(tbl->future_tbl, ht);
         if (iter->walker->tbl) {
                 iter->slot = 0;